I don?t use Google Images, so I ?can?t judge about this, but I?d be very careful about copying photos or graphics from the internet into an publicly visible site.
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The authors of pictures have numerous rights under copyright law; at least under German law the author alone determines whether and how his pictures may be used. If he discovers one of his fotos on a site other than his own, he can sue for compensation. This can cost thousands of dollars.
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For my publications I use pixabay. There are millions of pictures for free, but you mus register there. So you are on the safe side.